The valve has a tubular body, a lever journalled pivotably to the body for turning a valve means, as well as coupling elements at the forward end of said body for disconnectably coupling to it the connecting plug of a line, said coupling elements comprising a push-pull sleeve surrounding the forward end of the body.
A problem with such prior art bayonet catches for pneumatic lines is that, as the catch is opened, the working side pressure discharges at great force through a plug just disconnected with the consequence that the line might get out of hand and cause damage by hitting surrounding objects.
In order to overcome this problem, an object of the invention is to provide a bayonet catch that cannot be released until the working pressure within the coupling has been allowed to discharge to atmosphere in a controlled manner while the plug is still connected to the bayonet catch. This object is achieved by the invention on the basis of the characteristics set out in the annexed claims.